Low foaming rinse additive

ABSTRACT

LOW FCAMING RINSE ADDITIVES ARE PREPARED FROM A BLEND OF NONIONIC AND ANIONIC SURFACTANTS WHICH ARE WATER-SOLUBLE OR MISCIBLE AT TEMPERATURES ABOVE 180*F. THE NONIONIC SURFACTANTS WHICH ARE USED IN THE PRACTICE OF THIS INVENTION ARE MODIFIED OXYALKALATED LINEAR ALCOHOLS AND THE ANIONIC SURFACTANTS WHICH ARE USED IN THE PRACTICE OF THIS INVENTION ARE SULFOSUCCINIC ACID ESTERS OR PHOSPHATE ESTERS.

United States Patent Ofice 3,629,127 Patented Dec. 21, 1971 3,629,127 LOW FOAMING RINSE ADDITKVE Frank W. Palmer, Detroit, and Otto T. Aepli, Southgate, Mich., assignors to BASF Wyandotte Corporation, Wyandotte, Mich. No Drawing. Filed Aug. 5, 1968, Ser. No. 749,937

Int. Cl. Clld 1/12 US. Cl. 252--55 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to low foaming rinse aids. It is more particularly concerned with compositions exhibiting extremely good surface tension-lowering properties at temperatures up to and exceeding 180 F. It is also concerned with a rinse composition in a use solution which is miscible at temperatures up to and exceeding 180 F. In another aspect, the invention is concerned with rinse aid compositions for machine dishwashing.

Rinse additives have been used extensively in the past to reduce drying time and spotting while contributing to clean dishware. However, these rinse additives have been found to have an adverse effect on the operation of dishwashing machines over an extended period of time. This is usually due to foam formation caused by their own inherent chemical properties or by their use in conjunction with food soil found in the dishwashing machine. It has also been found that typical rinse additives of the low foaming variety do not remain soluble or completely miscible at temperatures exceeding 180 -F. Therefore, it was desirable to find a low foaming rinse additive which has the ability to reduce drying time and spotting while contributing to clean dishware, and yet be soluble or miscible at temperatures exceeding 180 F.

It is an object of this invention to provide a composi- .tion which is soluble over a Wide range of temperatures. It is a further object to provide a rinse additive having the properties of promoting rapid draining and drying of dishware. It is another object to provide a rinse additive that contributes to the elimination of spotting and streaking of dishware. It is an additional object to provide a rinse additive having low foaming properties over a wide range of temperatures. Other objects and advantages of this invention will become apparent to those skilled in the art upon consideration of the accompanying disclosure.

The present invention resides in a low foaming rinse additive. Broadly speaking, the low foaming rinse additive comprises a blend of nonionic and anionic surfactants. More specifically, the low foaming rinse aid composition of this invention consists essentially of from about 20 to 80 parts by weight of a nonionic surfactant which is a linear oxyalkylated alcohol; from about 5 to 10 parts by weight of an anionic surfactant which is a sulfosuccinic acid ester or a phosphate ester, or mixtures of sul-fosuccinic acid esters and phosphate esters; and from about 10 to 75 parts by weight water.

The linear oxyalkylated alcohols that may be used in the practice of this invention are those prepared by the condensation of an essentially linear primary aliphatic alcohol, or preferably a mixture of such alcohols, with a critical amount of a mixture of ethylene oxide and propylene oxide. These oxyalkylated alcohols are a cogeneric mixture of compounds that can be represented by the following formula:

R-O (A)H wherein R is an essentially linear alkyl group, and A is a mixture of oxyethylene and oxypropylene groups. The term cogeneric mixture, as used above, designates a series of closely related homologues that are obtained by condensing a plurality of oxide units with an alcohol or a mixture thereof. Preferred linear oxyalkylated alcohols that may be used are those wherein vR contains from 12 to 15 carbon atoms and A is a mixture of oxyethylene and oxypropylene groups wherein the molar ratio of oxypropylene to oxyethylene is from about 0.85:1 to 2.75:1, and the mixture of oxide units represents from about 55 to of the total weight of the compounds.

The sulfosuccinic acid esters that may be used in the practice of this invention are those having the formula:

wherein R and R are an alkyl group and 'M is an alkali metal or ammonia. Preferred sulfosuccinic acid esters are the sodium salts of a di-alkyl sulfosuccinic acid, wherein the alkyl groups are hexyl, octyl or isobutyl groups.

The anionic phosphate esters that may be used include the phosphate esters of oxyalkylated linear and oxyalkylated aromatic alcohols. These phosphate esters may be represented by the formulas:

OH RO (A) P OH (monoester) and [RO (A)] P-OH H (diester) wherein R is a linear alkyl group or an alkyl phenol and A is either specific oxyalkylene groups or a mixture of oxyalkylene groups. Preferred phosphate esters of oxyalkylated linear alcohols are those containing a mixture of monoesters and diesters wherein R in each ester contains from 10 to 12 carbon atoms and A is a mixture of oxyethylene and oxypropylene groups wherein the molar ratio of oxyethylene to oxypropylene is from about 4:1 to 8:1 and represents from about 45 to 80% of the total weight of the ester. The weight'of monoester in the preferred ester mix is from about 50% to about 70%, and the Weight of diester is from about 50% to about 30%. Preferred phosphate esters of oxyalkylated aromatic alcohols are those containing a mixture of monoesters and diesters wherein the alkylphenol is nonyl phenol and A is a plurality of oxyethylene groups repre senting from about 45 to 65% of the total weight of the ester. The weight of monoester in the preferred ester mix is from about 50% to about 70%, and the weight of diester is from about 50% to about 30%.

It has been found that amounts of rinse additive of the present invention varying from about 200 p.p.m. down to 10 p.p.m. work satisfactorily in a use solution. The wide range over which this rinse additive may be used is due to the properties of the specific nonionic and anionic surface active agents that are employed in forming the additive. The nonionic surfactant contributes to low surface tension at high temperatures and low foaming at low temperatures whereas the anionic surfactant acts as a coupling agent with water as Well as a stabilizer at high temperature.

A preferred method of preparing a using solution is to prepare initially a concentrate of a rinse additive by adding the nonionic surfactant to water at a temperature between about 75 and F. The mixture is stirred thoroughly and the anionic surfactant is added to the solution. The concentration of the ingredients in the concentrate will be in the aforementioned ranges. The resulting concentrate is then added to a use solution so as to provide a concentration of 10 p.p.m. to 200 p.p.m. concentrate in the solution at the desired operating temperature. It is to be understood that a mixture of the nonionic surfactants and/or a mixture of the anionic surfactants can be utilized in preparing the concentrate.

A more comprehensive understanding of the invention can be obtained by considering the following examples. However, it should be understood that the examples are not intended to be unduly limitative of the invention.

EXAMPLES I-II These examples describe runs in which the low foaming and surface tension properties of a rinse additive prepared according to the present invention were compared with commercially available low foaming rinse additives. The four rinse additives described below were used in these comparisons.

Rinse Additive A Rinse Additive A was a low foaming commercially available rinse additive containing 52 parts by weight of a polyoxyethylene-polyoxypropylene block copolymer, 5 parts by weight citric acid and 43 parts by weight water.

Rinse Additive B Rinse Additive C was a low foaming commercially available rinse additive containing 50 parts by weight of an organo phosphorus chelate, 5 parts by weight isopropyl alcohol, and parts, by weight of water.

Rinse Additive D Rinse Additive D was a low foaming rinse additive of the present invention containing 30 parts by weight of the condensation product of a mixture of linear primary aliphatic alcohols having from 12 to 15 carbon atoms with a mixture of propylene oxide and ethylene oxide, wherein the propylene oxide to ethylene oxide was in the molar ratio of about 2 to 1 and the oxide mixture represented about 75% of the total weight of the condensation product, 6 parts by weight of dihexyl sodium sulfosuccinic acid ester, and 64 parts by weight of water.

EXAMPLE I The following example illustrates the surface tension lowering properties of a rinse additive of the present invention when compared with commercially available rinse additives. The rinse additives compared were those described above.

The rinse additives were added to seven grain water in amounts sufficient to give from 10 to 200 parts per million concentration. The results were as follows:

TABLE 1 Rinse additive- B C D Concentration of additive in use solution Surface tension in dynes/em.

Parts or million:

10 3 45. l 44. t) 46. (1 54. S 43.2 45. T 4%. 7 312.3 41. 0 415.8 41. 6 31. b

1 Surface tensilen-ASTM D1331-5i3.

The above data illustrates that when use solutions of the same concentrations of rinse additives were compared, the use solution containing the additive of the present invention had better surface tension lowering properties than use solutions containing commercially available additives. The data further illustrates that the rinse additive of the present invention in a concentration of 10 p.p.m. in a use solution had equal or superior surface tension lowering properties when compared with commercially available additives which were used in concentrations of 50 p.p.m. in a use solution.

EXAMPLE II The following example illustrates the low foaming properties of a rinse additive prepared according to the present invention when compared with commercially available rinse additives. The rinse additives compared were those described above.

Use solutions were prepared by adding the rinse additives to seven grain water in amounts sufficient to give and 200 parts per million concentration. The low foaming properties of the use solutions were determined by adding 300 ml. of a use solution to a one liter graduate, bubbling air into the graduate at the rate of 425 cc./min. for a period of 1 to 2 minutes, and then reading the increase in foam height in milliliters (ml.). The temperature of the use solution was then increased by 20 F. and the above procedure was repeated. The low foaming properties were determined for the temperature range of 100 to 180 F. After the low foaming properties of the use solution were determined, a predetermined amount of food soil was added to each solution, and the low foaming tests, as described above, were repeated. The food soil tests consisted of 0.1% by weight of egg in one series of runs and 1.0% by weight of milk in another series of runs. The tables below illustrate the results of these runs.

TABLE 2.FOAMING PROPERTIESNO SOIL Increased foam height in ml.

TABLE 3.FOAMING PROPERTIES-0.1% EGG Increased ioarn height in ml.

A B C D Rinse additives, p.p.m 100 200 100 200 100 200 100 200 TABLE 4.FOAMING PROPERTIES1.0% MILK Increased foam height in ml.

A B C D Rinse additives,p.p.m 100 200 100 200 100 200 100 200 Temperature, F.:

In commercial operations, the Washing of dishware is generally accomplished in three stagesscraping, washing, and rinsing. The scraping, or first stage in the dishwashing operation, is usually maintained at a temperature of from about to F. The wash, or

second stage in the dishwashing operation, is usually maintained at a temperature of from about 140 to 160 F., and the rinse, or last stage in the dishwashing operation, is usually maintained at a temperature of from about 160 to 170 F. The food soil load is highest in the scraping stage, lower in the wash, and ne ligible in the rinse stage.

In order to conserve heat and water, it is customary to feed back solution from the rinse stage to the wash or scraping stage. Therefore, the use solution at the scraping stagewill contain low rinse additive, due to dilution with water, low temperature, and high food soil. It is under such conditions that commercially available rinse additives in use solutions foam.

From the above tables, it can be seen that the foaming properties of the rinse additives of the present invention, both under soil load and under no load conditions at commercial operating temperatures, exhibit very little foaming tendencies whereas the commercially available products show tendencies to foam.

EXAMPLES III-IV These examples illustrate the degree of water spotting after rinsing and the low foaming properties of rinse additives prepared according to the present invention. The following table describes the compositions of the three rinse aids used in these tests.

TABLE Rinse additive E F G Parts by Weight:

Nonionic I 2 3O 56 H (monoester) O OH and where in R was nonyl phenol and A was a plurality of oxyethylene groups representing from about 55% to about 65% of the total weight of the compounds. The percent by Weight of monoester was about 55% and the percent by weight of diester was about 45%.

f ALlL11iOnlG III-A mixture of phosphate esters represented by the arm as:

RO (A) F (monoester) wherein R was a mixture of alkyl groups having from 10 to 12 carbon atoms and A Was a mixture of oxyethylene and oxypropylene groups wherein the molar ratio of oxyethylene to oxypropylene was about 6 to 1 and the oxyethylene-oxypropylene groups represented from about 60 to 80% of the total weight of the compounds. The percent by weight of monoester was about 55% and the percent by weight of dieslter was about 45%.

EXAMPLE III The following example illustrates the low foaming properties of rinse additives prepared according to the present invention. The rinse additives tested were those illustrated in Table 5.

Use solutions where prepared by adding the rinse additives to seven grain water in amounts sufficient to give 100 and 200 parts per million concentration. The low foaming properties of use solutions were determined by adding 300 ml. of a use solution into a one liter graduate, bubbling air into the graduate at the rate of 425 cc./ min. for a period of 1 to 2 minutes, then reading the increase in the foam height in milliliters. The temperature of the use solution was then increased by F. and the 10 above procedure was repeated. The low foaming properties were determined for the temperature range of 110 to 180 F. After the low foaming properties of the use solution were determined, a predetermined amount of food soil was added to each solution, and the low foaming 1 tests, as described above, were repeated. The food soil tests consisted of 0.1% by weight of egg in one series of runs and 1.0% by weight of milk in another series of runs. The tables below illustrate the results of these runs.

0 TABLE 6.FOAMING PROPERTIESNO SOIL Increased foam height in ml.

E F G Rinse additives, ppm. 100 200 100 200 100 200 Temperature, F.:

110 25 5 5 5 25 50 5 0 0 0 l0 (l0 0 O 0 0 0 00 0 0 0 5 0 00 TABLE 7.FOAMING PROPERTIES-0.1% EGG Increased foam height in ml.

E F G Rinse additives, ppm. 100 200 100 200 100 200 5 Temperature, F.:

40 TABLE 8.FOAMING PROPERTIE s 1.0% MILK Increased foam height in ml.

E F G Rinse additives, ppm. 100 200 100 200 100 200 50 From the above data it can be seen that the rinse The following example illustrates the degree of water spotting after rinsing with a use solution prepared from rinse additives prepared according to the present invention. The rinse additives tested were those described in 5 Table 5.

The tests were carried out by loading a Hotpoint dishwasher with four glasses. The dishwasher was then turned on and brought up to a wash temperature of 135 :5 F. During the wash cycle, 25 ml. of milk was added in order to soil the glasses and give them a hydrophobic or water spotted condition. As soon as the machine went into its rinse cycle, 7.5 ml. (50 ppm. in use solution) of the candidate rinse additive was added. The dishwasher was then allowed to complete its rinse and drying cycles. The

glasses were then allowed to cool to room temperature and were then observed in a black box for spotting or filming according to the following method of rating:

No spots or film A spotted or filmed /2 spotted or filmed spotted or filmed Completely spotted or filmed After the four glasses had been evaluated, they were returned to the dishwasher soiled, and 15 ml. of the candidate rinse additive was added to the rinse or use solution. This gave a concentration of 100 p.p.m. of additive in the use solution. The rinse temperature was brought up to 135:5 F. and the rinse, drying, and cooling was repeated in the same manner as above. The glasses were then observed in the black box and rated in the same manner as before.

The four glasses were also evaluated a third time wherein the use solution had a concentrate of 150 p.p.m. of rinse additive, and then a fourth and final time, at 200 p.p.m. concentration of rinse additive.

The above series of rinses were repeated for each of the rinse additives described in Table 5. The results of the tests are illustrated in Table 9 below.

TABLE 9 Rating of glasses Rinse additive:

As can be seen from the above data, at rinse additive concentrations of 50 to 200 p.p.m. in a rinse solution, the rinse additives prepared in accordance with the present invention are effective for the prevention of spotting or film forming after rinsing.

What is claimed is:

1. A rinse additive composition consisting essentially of:

(a) about 20 to 80 parts by weight of a linear oxyalkylated alcohol which is the condensation product of a mixture of linear primary aliphatic alcohols having from 12 to 15 carbon atoms with a mixture of propylene oxide and ethylene oxide wherein the molar ratio of propylene oxide to ethylene oxide is from about 0.85 :1 to 2.75 :1 and the mixture of oxide units represents from about 55 to 80% of the total weight of the condensation product;

(b) about to parts by weight of an anionic surfactant which is either (1) a sulfosuccinic acid ester which corresponds to the formula:

nlooo-on n oooons 0311 wherein R and R are octyl, hexyl, or isobutyl groups and M is alkali metal or ammonia or (2) a phosphate ester selected from the group consisting 8 of (a) a mixture of phosphate monoand diesters having the formulas:

OH RO(A)T|1T O OH and

[R-O(A)]2{|OH wherein R is an alkyl group having from 10 to 12 carbon atoms, and A is a mixture of oxyethylene and oxypropylene wherein the ratio of oxyethylene groups to oxypropylene groups is from about 4:1 to 8:1 and represents from about to about 80% of the total weight of the esters, and the monoester represents from about to 70% by weight of the mix, and the diester represents from about 50 to 30% by weight of the mix, and (b) a mixture of phosphate monoand diesters having the formulas:

wherein R is a nonyl phenol and A is a plurality of oxyethylene groups representing from about 45% to by weight of the mix, and the monoester represents from about 50 to by weight of the mix and the diester represents from about 50 to 30% by weight of the mix, and ,(c) about 10 to parts by weight of water. 2. The composition of claim 1 wherein the anionic surfactant is the sulfosuccinic acid ester.

3. The composition of claim 1 wherein the anionic surfactant is the phosphate ester mixture of phosphate monoand diesters having the formulas:

wherein R is an alkyl group having from 10 to 12 carbon atoms, and A is a mixture of oxyethylene and oxypropylene wherein the ratio of oxyethylene groups to oxypropylene groups is from about 4:1 to 8:1 and represents from about 45 to about of the total weight of the esters, and the monoester represents from about 50 to 70% by weight of the mix, and the diester represents from about 50 to 30% by weight of the mix.

4. The composition of claim 1 wherein the anionic surfactant is-the phosphate ester mixture of phosphate monoand diesters having the formulas:

wherein R is a nonyl phenol and A is a plurality of oxyethylene groups representing from about 45% to about 65% by weight of the mix, and the monoester represents from about 50 to 70% by weight of the mix and the diester represents from about 50 to 30% by weight of the mix.

5. A use solution consisting essentially of the composition of claim 1 wherein the concentration of the rinse additive is from about 10 to 200 p.p.m. in the use solution.

hexyl and M is sodium.

6. The composition of claim 2 wherein R and R are 3,122,508 3,314,891 3,329,615 References Cited 3,382,174 UNITED STATES PATENTS 5 1/1936 Jaegar 252-161 10/1961 Nunn et a1. 260951 10/1961 Nunn 26098O 5/1962 Chiddix et a1. 25289 3/1963 Temple et a1 252-439 10 252459 538 l0 Grifo et a] 252135 Schmolka et a1 252-89 Cooper et a1 252135 Lissant et a1. 252135 LEON D. ROSDOL, Primary Examiner W. R. SCHULZ, Assistant Examiner US. Cl. X.R. 

